#include <stdio.h>

int a = 10000;
int c = 8400;
int b;
int d;
int e;
int g;
int f[8401];
float p;

int main(void)
{
  for( b = 0 ; b < c ; b++ ) {
    f[b] = a / 5;
  }
  e = 0;
  for( c = 8400 ; c > 0 ; c -= 14 ) {
    d = 0;
    for( b = c - 1 ; b > 0 ; b-- ) {
      g = 2 * b - 1;
      d = d * b + f[b] * a;
      f[b] = d % g;
      d /= g;
    }
    if(c==8400){
      p=e+d / a;
      p/=1000;
      printf("%5.3f", p);
    }
    else{
      printf("%04d", e + d / a);
    }
    e = d % a;
  }
  return 0;
}
// Reference URL:http://xn--w6q13e505b.jp/